Noise management for venues
Usually, a noise limit is set, and if you go above it, penalties apply.
It is set at a fixed position in the venue and calibrated to a lower noise level at the receiving point (usually neighbour). For example, if anything over 105 dB LAeq inside the venue causes excessive noise at a neighbouring receiver, the limit will be set at 105. It is usually measured at 3m from the PA system.
This is very common and suffers a multitude of problems...
1. Limiters are installed in the venue to prevent going over the noise limit. They either, turn the power to the PA system off when the limit is exceeded, or compress the music when the limit is exceeded.
The power cut off system does give some warning but once it cuts off there is silence until it resets. There is a great story about a wedding for a very wealthy couple where the band was nicely under the limit, until someone started dancing wildly and the guests all started cheering and screaming. The limiter turned the sound off at that point and the rest is obvious....
All sorts of illegal bypass methods are tried including covering the microphone and dangerous bypass wiring
The compression style limiter does not turn the sound off but tries to turn it down as the music gets louder, and in doing so destroys the sound of the music.
The most common problem with this type of limiter is DJs and sound engineers who either don't understand how they work or don't know they are installed. As they try to increase the sound level in the venue the limiter is “fighting” their efforts. They then try harder to increase the sound level so the limiter compresses the sound even more, until they give up in disgust and blame the PA system for sounding bad.
2. When a neighbour complains about noise from a venue it can be checked at the neighbour's property. The level is usually set at a small amount above background noise. Background noise is measured over a long period of time to average out spurious noises like vehicles passing. However, if there is more than one noise source at the time of complaint, things get difficult. For example, an area with bars and restaurants will have all of them contributing to the noise on a Friday or Saturday night. If a neighbour complains, it is really impossible to determine which one is responsible. Even if one is a little louder than normal, but still under it's own limit, the sum of all sources may be above the limit at the neighbour's property.
3. When setting noise limits, regulators use the sound energy equivalent to that of a constant sound pressure level for a set period of time – NOT the sound pressure level at any instant. This is to help the measurement align to the human hearing system and what it finds objectionable. The limit may be specified in units of LaeqdB or L10 dB. Venues using cheap sound level meters are not only relying on inaccurate equipment but they are measuring the wrong thing. Sound Pressure level (SPL) is not Laeq dB or L10 dB, and the heated arguments starting with “but we had our sound level meter on all night and never went over the limit” are futile. It's a bit like having a 60km/h speed limit and saying “but I only went 30 metres”.
4. So what is the ideal situation?
No power being switched off or compressed.
Being able to prove that the venue complied with the Laeq dB or L10 dB limit using a high quality system that securely logs all measurements for proof.
Showing that the limit was not exceeded inside the venue and therefore complaints must be from other or cumulative noise.
Ideally, a system that calculates the current Laeq dB and looks at the trend to give a “prediction” of if and when a limit may be exceeded in the future(remember, the limit is total energy equivalent to a constant level for a period of time, so it can be calculated on the fly). This allows a manager, DJ or engineer to simply turn it down a little.
The solution - the system of choice is called 10EaZy. It is a unique and intelligent design that succeeds because it considers the viewpoint of the regulator, venue, sound engineer/DJ and patron. 10EazY is even legislated for all venues in some countries.
Interestingly, feedback has shown that not only are limits managed better but sound engineers have have focussed more on creating a good mix than just turning it up!
For more information, acoustic advice or pricing, please contact us at;
07 3103 0591
or go to the 10EaZy products page here.